This invention relates to compositions of matter and methods of using them for passivating various industrial process equipment, in particular certain compositions that have been found to be particularly effective in reducing the deposition of foulants in petroleum processing equipment.
Passivation is the process of making a material “passive” (non-reactive) in relation to another material prior to using the two materials together. Some examples of passivation are described in U.S. Pat. Nos. 4,024,050, 3,522,093, 6,228,253, ASTM A-967, and ASTM A-380. In the context of petroleum processing equipment, one common method of passivating the equipment is phosphate passivation. Phosphate passivation involves coating the surface of the equipment with a layer of phosphates that prevents reactions between the petroleum materials the equipment walls. Two known methods of phosphate passivation are amine neutralized phosphate ester treatment and acid phosphate ester treatment such as that described in articles: Comparative characteristics of phosphate-containing inhibitors for neutral media, by V F Sorochenko et al., Politekh. Inst., Kiev, Ukraine. Neftepererabotka i Neftekhimiya (Kiev) (1993), volume 44 pages 82-89 Publisher: Naukova Dumka, and Stream analysis, failure analysis and laboratory tests show effect of hydrogen sulfide and phosphorous-based inhibitors, by Babaian-Kibala et al., Fuel Reformulation (1994), Volume 4(1), pages 43-48. Although both of these methods produce an iron phosphate coating, each has drawbacks. The amine neutralized phosphate ester treatment produces a thin film, which unfortunately deteriorates quickly. The acid phosphate ester treatment may result in a reactive polyphosphate coating, which reacts with sodium and calcium cations in the petroleum material that promotes unwanted coke formations.
Thus there is clear need and utility for an improved method of passivating industrial process equipment used in processing petroleum material. The art described in this section is not intended to constitute an admission that any patent, publication or other information referred to herein is “prior art” with respect to this invention, unless specifically designated as such. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 C.F.R. §1.56(a) exists.